Ive always interpreted this as the amount of minutes left in the boil. Most boils are a standard 60 minutes on average. So with this a 60minute addition is right at the beginning vs a 5minute addition is right close to the end of the boil. Based on a 60 minute boil time, your question about a 30minute addition is like asking is the glass half empty or half full as this is right in the middle . Cheers!